Ascent™ Combi Boiler
High Efficiency Tankless Coil Boiler Alternative
Roger Marran
Research and
Development
Sponsor:
Why does oilheat need an alternative
to tankless coil boilers?
Customer satisfaction:
1) Better Hot Water Quality
2) Higher Efficiency
3) Quiet Operation
Industry Perception:
Fuel Conversions vs Tankless Coils
• Oilheat appears inefficient
• Oilheat is loud
• Oilheat runs out of hot water
This false impression is Product
based, not Fuel based!
Ascent™ Combi Boiler Design Criteria
1) Competitive Price
2) Drop-in Replacement for
Tankless Coil
3) Better Efficiency with Lower
Idle Loss
4) Better Hot Water Temperature
and Comfort
5) Long Life Pressure Vessel
6) Hard Water Serviceability
Options
Whisper Quiet Operation
Hot water operating modes
Ascent™ Combi Inside Look
Stainless Alloy
Combustion Chamber
Ascent Hydrostat
Limit and LWCO
Optimized for Hot Water
(no zone controller)
Swing Down Door
Proven 30 Year
Spiral Boiler Design
Ascent™ Combi CIP and Features
Mixing Valve
(CIP)
Flow Switch
Clean in Place (CIP) Valve for Plate
Heat Exchanger and Mixing Valve
Air Elimination Heat Exchanger (CIP)
Hydronic
Y-Strainer LEFT SIDE
VIEW (Top Removed)
1 GPH Tankless Coil Boiler (2.6% Idle Loss) 916 Gallons per Year
*Based on preliminary testing data
Estimate: Save 191 gallons and 20.8%
1 GPH Ascent Combi (0.92% Idle Loss) 725 Gallons per Year
*Based on preliminary testing data
Ascent™ Combi Hot Water Modes
Simple Operating Modes (easy select)
1) Always Ready Instantaneous Hot Water (Plate Warming Mode)
2) On Demand…hot water is ready in about 2 minutes from cold start (winter ready with heat calls)
3) Smart Learning – no delay
Two Quick on/offs of the
hot water tap signal
Ascent to make hot water
Ascent™ Combi Hot Water Output
Nearly 4 GPM
Continuous Flow with
77° F Rise
Much better than tankless
coil boiler hot water.
*For high flow showers, fast fill
tubs, and even higher efficiency,
System 2000 is recommended
3-section Tankless Coil Boiler Fired @ 0.95gph, 2.5gpm water flow rate 120° DHW target 180° boiler set point with mixing valve
Slow recovery and small ΔT Over 10°F off setpoint
Poor temperature control (even at moderate flow rates)
Coil Out
Mix
Tankless Coil Hot Water with Mixing Valve
10 minute draw
Cold Make-up
Energy Kinetics Ascent Combi Boiler Fired @ 1.00gph, 2.5gpm water flow rate 120° DHW target, 170° boiler setpoint Same mixing valve installed
Minimal spikes in temperature – mix valve stays within ASSE 1017 limits (+/- 2°F)
Fast recovery and large ΔT
Heat
Exchanger
Out
Mix
Cold Make-up
Ascent Combi Hot Water
10 minute draw
Ascent™ Combi Brochures
Dilution Air
Venting
An Enabling Technology
for Oilheat Advances
Outside
Air
Polypropylene
Vent
90+ Resolute™ 6 Years Proven Performance
Research and
Development
Sponsors:
Chimneys Applications
• Can require a liner
$2,000 to $3,000
• Consumer fuel switching
• Low cost plastic venting
helped make gas water heaters
a competitive option
Bring lower cost reliable
options to Oilheat
Dilution venting
A page out of the water heater playbook…
Dilution
air
Flue Gas
Mixed
Flue Gas
Venting Solutions (Centrotherm Example)
Installation Flexibility
with multiple venting options
Sidewall low profile Through the roof Flex Chimney
Vent with 3” Polypropylene or Stainless Steel (cleanable)
248°F Max Flue Temperature Rating for Oilheat (100°F to 150°F)
Pipe air intake with PVC or Polypropylene
Maximum length 50’ equiv. intake plus 50’ equiv. exhaust
Address Design Concerns Cold weather
Will it condense?
How cold is too cold?
Impact on components?
Humid make up on hot summer
days? Lower relative humidity with burner running.
Vent system condensing? No. Provision for rain or condensate built in.
Wind loads? 60 MPH sustained winds, 80 MPH gusts
Burner Clean Operation? Light off comparable to a very good chimney (no
draft loss on light off)
Chamber delivers exceptionally clean performance
at low and high draft, cold and warm temperatures
Calculation Results Example
Field Results: Fairbanks Alaska Combination Hood
Stainless Steel “Nozzle”
Combination hood preheats dilution air.
No issues at sustained -60°F temperatures.
Condensing gas boiler hotel example.
Temperature: -50°F
Venting Vertically with 3”
Centrotherm Flex
Polypropylene
Air intake from side wall
-or-
Second Flex line
Rain Trap at Thimble
(dries out)
No draft regulator
90+ Resolute Boiler 6 Years Proven Performance
0.68 GPH to 1.0 GPH
Multi-Fuel
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